diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4bb761bd96..e6dd704c5b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,5 @@
 <!--
-## 2023.x.x (unreleased)
+## 202x.x.x (unreleased)
 
 ### General
 -
@@ -38,6 +38,7 @@
 - Enhance: 絵文字ピッカー・オートコンプリートで、完全一致した絵文字を優先的に表示するように
 - Enhance: Playの説明欄にMFMを使えるように
 - Enhance: チャンネルノートの場合は詳細ページからその前後のノートを見れるように
+- Enhance: MFMの属性でオートコンプリートが使用できるように #12735
 - Fix: ネイティブモードの絵文字がモノクロにならないように
 - Fix: v2023.12.0で追加された「モデレーターがユーザーのアイコンもしくはバナー画像を未設定状態にできる機能」が管理画面上で正しく表示されていない問題を修正
 - Fix: AiScriptの`readline`関数が不正な値を返すことがある問題のv2023.12.0時点での修正がPlay以外に適用されていないのを修正
diff --git a/packages/frontend/src/components/MkAutocomplete.vue b/packages/frontend/src/components/MkAutocomplete.vue
index 15eda4499f..9d03eab2cb 100644
--- a/packages/frontend/src/components/MkAutocomplete.vue
+++ b/packages/frontend/src/components/MkAutocomplete.vue
@@ -35,6 +35,11 @@ SPDX-License-Identifier: AGPL-3.0-only
 			<span>{{ tag }}</span>
 		</li>
 	</ol>
+	<ol v-else-if="mfmParams.length > 0" ref="suggests" :class="$style.list">
+		<li v-for="param in mfmParams" tabindex="-1" :class="$style.item" @click="complete(type, q.params.toSpliced(-1, 1, param).join(','))" @keydown="onKeydown">
+			<span>{{ param }}</span>
+		</li>
+	</ol>
 </div>
 </template>
 
@@ -51,7 +56,7 @@ import { emojilist, getEmojiName } from '@/scripts/emojilist.js';
 import { i18n } from '@/i18n.js';
 import { miLocalStorage } from '@/local-storage.js';
 import { customEmojis } from '@/custom-emojis.js';
-import { MFM_TAGS } from '@/const.js';
+import { MFM_TAGS, MFM_PARAMS } from '@/const.js';
 
 type EmojiDef = {
 	emoji: string;
@@ -130,7 +135,7 @@ export default {
 <script lang="ts" setup>
 const props = defineProps<{
 	type: string;
-	q: string | null;
+	q: any;
 	textarea: HTMLTextAreaElement;
 	close: () => void;
 	x: number;
@@ -151,6 +156,7 @@ const hashtags = ref<any[]>([]);
 const emojis = ref<(EmojiDef)[]>([]);
 const items = ref<Element[] | HTMLCollection>([]);
 const mfmTags = ref<string[]>([]);
+const mfmParams = ref<string[]>([]);
 const select = ref(-1);
 const zIndex = os.claimZIndex('high');
 
@@ -251,6 +257,13 @@ function exec() {
 		}
 
 		mfmTags.value = MFM_TAGS.filter(tag => tag.startsWith(props.q ?? ''));
+	} else if (props.type === 'mfmParam') {
+		if (props.q.params.at(-1) === '') {
+			mfmParams.value = MFM_PARAMS[props.q.tag] ?? [];
+			return;
+		}
+
+		mfmParams.value = MFM_PARAMS[props.q.tag].filter(param => param.startsWith(props.q.params.at(-1) ?? ''));
 	}
 }
 
diff --git a/packages/frontend/src/const.ts b/packages/frontend/src/const.ts
index ea07204456..38d0d85eef 100644
--- a/packages/frontend/src/const.ts
+++ b/packages/frontend/src/const.ts
@@ -109,3 +109,27 @@ export const DEFAULT_NOT_FOUND_IMAGE_URL = 'https://xn--931a.moe/assets/not-foun
 export const DEFAULT_INFO_IMAGE_URL = 'https://xn--931a.moe/assets/info.jpg';
 
 export const MFM_TAGS = ['tada', 'jelly', 'twitch', 'shake', 'spin', 'jump', 'bounce', 'flip', 'x2', 'x3', 'x4', 'scale', 'position', 'fg', 'bg', 'border', 'font', 'blur', 'rainbow', 'sparkle', 'rotate', 'ruby', 'unixtime'];
+export const MFM_PARAMS: Record<typeof MFM_TAGS[number], string[]> = {
+	tada: ['speed=', 'delay='],
+	jelly: ['speed=', 'delay='],
+	twitch: ['speed=', 'delay='],
+	shake: ['speed=', 'delay='],
+	spin: ['speed=', 'delay=', 'left', 'alternate', 'x', 'y'],
+	jump: ['speed=', 'delay='],
+	bounce: ['speed=', 'delay='],
+	flip: ['h', 'v'],
+	x2: [],
+	x3: [],
+	x4: [],
+	scale: ['x=', 'y='],
+	position: ['x=', 'y='],
+	fg: ['color='],
+	bg: ['color='],
+  border: ['width=', 'style=', 'color=', 'radius=', 'noclip'],
+	font: ['serif', 'monospace', 'cursive', 'fantasy', 'emoji', 'math'],
+	blur: [],
+	rainbow: ['speed=', 'delay='],
+	rotate: ['deg='],
+	ruby: [],
+	unixtime: [],
+};
diff --git a/packages/frontend/src/scripts/autocomplete.ts b/packages/frontend/src/scripts/autocomplete.ts
index 2a9a42ace5..b0c36cb927 100644
--- a/packages/frontend/src/scripts/autocomplete.ts
+++ b/packages/frontend/src/scripts/autocomplete.ts
@@ -8,13 +8,13 @@ import getCaretCoordinates from 'textarea-caret';
 import { toASCII } from 'punycode/';
 import { popup } from '@/os.js';
 
-export type SuggestionType = 'user' | 'hashtag' | 'emoji' | 'mfmTag';
+export type SuggestionType = 'user' | 'hashtag' | 'emoji' | 'mfmTag' | 'mfmParam';
 
 export class Autocomplete {
 	private suggestion: {
 		x: Ref<number>;
 		y: Ref<number>;
-		q: Ref<string | null>;
+		q: Ref<any>;
 		close: () => void;
 	} | null;
 	private textarea: HTMLInputElement | HTMLTextAreaElement;
@@ -49,7 +49,7 @@ export class Autocomplete {
 		this.textarea = textarea;
 		this.textRef = textRef;
 		this.opening = false;
-		this.onlyType = onlyType ?? ['user', 'hashtag', 'emoji', 'mfmTag'];
+		this.onlyType = onlyType ?? ['user', 'hashtag', 'emoji', 'mfmTag', 'mfmParam'];
 
 		this.attach();
 	}
@@ -80,6 +80,7 @@ export class Autocomplete {
 		const hashtagIndex = text.lastIndexOf('#');
 		const emojiIndex = text.lastIndexOf(':');
 		const mfmTagIndex = text.lastIndexOf('$');
+		const mfmParamIndex = text.lastIndexOf('.');
 
 		const max = Math.max(
 			mentionIndex,
@@ -94,7 +95,8 @@ export class Autocomplete {
 
 		const isMention = mentionIndex !== -1;
 		const isHashtag = hashtagIndex !== -1;
-		const isMfmTag = mfmTagIndex !== -1;
+		const isMfmParam = mfmParamIndex !== -1 && text.split(/\$\[[a-zA-Z]+/).pop()?.includes('.');
+		const isMfmTag = mfmTagIndex !== -1 && !isMfmParam;
 		const isEmoji = emojiIndex !== -1 && text.split(/:[a-z0-9_+\-]+:/).pop()!.includes(':');
 
 		let opened = false;
@@ -134,6 +136,17 @@ export class Autocomplete {
 			}
 		}
 
+		if (isMfmParam && !opened && this.onlyType.includes('mfmParam')) {
+			const mfmParam = text.substring(mfmParamIndex + 1);
+			if (!mfmParam.includes(' ')) {
+				this.open('mfmParam', {
+					tag: text.substring(mfmTagIndex + 2, mfmParamIndex),
+					params: mfmParam.split(','),
+				});
+				opened = true;
+			}
+		}
+
 		if (!opened) {
 			this.close();
 		}
@@ -142,7 +155,7 @@ export class Autocomplete {
 	/**
 	 * サジェストを提示します。
 	 */
-	private async open(type: string, q: string | null) {
+	private async open(type: string, q: any) {
 		if (type !== this.currentType) {
 			this.close();
 		}
@@ -280,6 +293,22 @@ export class Autocomplete {
 				const pos = trimmedBefore.length + (value.length + 3);
 				this.textarea.setSelectionRange(pos, pos);
 			});
+		} else if (type === 'mfmParam') {
+			const source = this.text;
+
+			const before = source.substring(0, caret);
+			const trimmedBefore = before.substring(0, before.lastIndexOf('.'));
+			const after = source.substring(caret);
+
+			// 挿入
+			this.text = `${trimmedBefore}.${value}${after}`;
+
+			// キャレットを戻す
+			nextTick(() => {
+				this.textarea.focus();
+				const pos = trimmedBefore.length + (value.length + 1);
+				this.textarea.setSelectionRange(pos, pos);
+			});
 		}
 	}
 }